In medical school they tell you half of what you are about to learn won't be true when you graduate - they just don't know which half. In every field of knowledge, half of what is true today will overturned, replaced, or refined at some point, and it turns out that we actually know when that will be for many things. In this episode, listen as author and scientist Sam Arbesman explains how understanding the half life of facts can lead to better lives, institutions, and, of course, better science.